Melting Behavior of the Feedstock

  • Frank Czerwinski

There are many requirements imposed on the potential feedstock, including size uniformity with a minimum of submicron fines, an oxide-free surface, smooth flow through the system and acceptable manufacturing cost. The key feature that determines its use for semisolid processing is, however, the formation of spheroidal particles of the unmelted phase within the semisolid slurry. The melting characteristics are sometimes seen as independent of the feedstock nature, and it is claimed that the alloy turns thixotropic during its conveyance through an extruder, due to the combined effect of shear imposed by the injection screw and external heating. To explain this, a description of the microstructural evolution of an alloy during processing and an assessment of the individual contributions of shear and heat are required. In this description, the role that a specific nature of feedstock plays needs to be established. This knowledge is important in the design of machinery that will better meet the requirements of semisolid processing.


Differential Thermal Analysis Magnesium Alloy Solid Fraction Triple Junction Extrusion Direction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Dieter GE (1976) Mechanical Metallurgy. McGraw-Hill, New YorkGoogle Scholar
  2. 2.
    Partidge PG (1967) Metals Review 12:167Google Scholar
  3. 3.
    McQueen HJ (2003) Comments on “On the generation of thixotropic structures during melting of Mg-9Al-1Zn alloy” by F Czerwinski. Scripta Materialia 49(8):917–920CrossRefGoogle Scholar
  4. 4.
    Gehrman R, Gottstein G (1999) In ICOTOM 12, Montreal, 1999, NSERC Press, Ottawa, Canada pp 665–670Google Scholar
  5. 5.
    Roberts CS (1960) Magnesium and Its Alloys. John Wiley & Sons, New YorkGoogle Scholar
  6. 6.
    Wang X, Brunger E, Gottstein G (2002) The role of twinning during dynamic recrystallization in alloy 800H. Scripta Materialia 46(12):875–880CrossRefGoogle Scholar
  7. 7.
    Galiev A, Kaibyshev R, Gottstein G (2001) Correlation of plastic deformation and dynamic recrystallization in magnesium alloy ZK60. Acta Materialia 49(7):1199–1207CrossRefGoogle Scholar
  8. 8.
    Kaibyshev R, Galiev A, Sokolov BK (1994) Physics of Metals and Metallography 78:209Google Scholar
  9. 9.
    Mabuchi M et al (1999) Low temperature superplasticity of AZ91 magnesium alloy with non-equilibrium grain boundaries. Acta Materialia 47(7):2047–2057CrossRefGoogle Scholar
  10. 10.
    Uggowitzer PJ, Wahlen A (2000) On the formation of eutectic phase in magnesium alloys during cooling from the semisolid state. In 6th conference on semisolid processing of alloys and composites, Turin, Italy, 2000. 429–435Google Scholar
  11. 11.
    Glickman EE, Nathan M (1999) Journal of Applied Physics 85:3185CrossRefGoogle Scholar
  12. 12.
    Rabkin E et al (2000) Diffusion-induced grain boundary porosity in NiAl. Scripta Materialia 42(11):1031–1037CrossRefGoogle Scholar
  13. 13.
    Chatain D et al (2001) Role of the solid liquid interface faceting in rapid penetration of a liquid phase along grain boundaries. Acta Materialia 49:1123–1128CrossRefGoogle Scholar
  14. 14.
    Boettinger WJ, Kattner UR (2002) On DTA curves for the melting and freezing of alloys. Metallurgical Materials Transactions A 33:1779–1794CrossRefGoogle Scholar
  15. 15.
    Mirkovic D, Grobner J, Schmid-Fetzer R (2004) Determination of solidification curves based on DSC experiments with improved heat-transfer model. In DM Herlach (ed) Solidification and Crystallization. Wiley-VCH, Weinheim, pp 95–102Google Scholar
  16. 16.
    Riddle YW, Makhlouf M (2003) Characterizing solidification by non-equilibrium thermal analysis. In HI Kaplan (ed) Magnesium Technology 2003, TMS, Warrendale, PA, pp 101–205Google Scholar
  17. 17.
    Tamminen J (1988) Thermal analysis for investigation of solidification mechanisms in metals and alloys. PhD Thesis, University of Stockholm, SwedenGoogle Scholar
  18. 18.
    Mirkovic D, Grobner J, Schmid-Fetzer R (2000) An approach to determine solidification curves of commercial magnesium alloys. In KU Kainer (ed) Magnesium alloys and their applications. DGM Wiley-VCH, Weinheim, pp 783–788Google Scholar
  19. 19.
    Gray AP (1968) Analytical Calorimetry. Plenum Press, New YorkGoogle Scholar
  20. 20.
    Flemings MC (1974) Solidification Processes. McGraw-Hill, New YorkGoogle Scholar
  21. 21.
    Okamoto H (1998) Journal of Phase Equilibria 19:598CrossRefGoogle Scholar
  22. 22.
    Wang H et al (2000) Materials Science Forum 329–330:449CrossRefGoogle Scholar
  23. 23.
    Wang JL, Su YH, Tsao CYA (1997) Structural evolution of conventional cast dendritic and spray-cast non-dendritic structures during isothermal holding in the semisolid state. Scripta Materialia 37(12):2003–2007CrossRefGoogle Scholar
  24. 24.
    Xia K, Tausing G (1998) Liquidus casting of a wrought alloy 2618 for thixoforming. Materials Science and Engineering A 246(1–2):1–10CrossRefGoogle Scholar
  25. 25.
    Czerwinski F et al (2001) Correlating the microstructure and tensile properties of thixomolded AZ91 magnesium alloy. Acta Materialia 49(7):1225–1235CrossRefGoogle Scholar
  26. 26.
    Zavaliangos A, Lin JC, Yin M (2000) In Sixth conference on semisolid processing of alloys and composites, Turin, Italy, 2000, pp 463Google Scholar
  27. 27.
    Snyder VA et al (1999) The influence of temperature gradient on Ostwald ripening. Metallurgical and Materials Transactions 30A(9):2343–2348Google Scholar
  28. 28.
    Wolfsdorf Brenner TL, Voorhees W, Sutliff, J (1999) Metallurgical and Materials Transactions 30A:1995Google Scholar
  29. 29.
    Fan D et al (2002) Phase-field simulation of 2-D Ostwald ripening in the high volume fraction regime. Acta Materialia 50(8):1895–1907CrossRefGoogle Scholar
  30. 30.
    Annavarapu S, Doherty RS (1995) Inhibited coarsening of solid-liquid microstructure in spray casting of high volume fraction of solid. Acta Metallurgica and Materialia 43(8):3207–3230CrossRefGoogle Scholar
  31. 31.
    Czerwinski F, Zielinska-Lipiec A (2003) The melting behaviour of extruded Mg-8Al-2Zn alloy. Acta Materialia 51(11):3319–3332CrossRefGoogle Scholar
  32. 32.
    Czerwinski F (2002) On the generation of thixotropic structures during melting of Mg-9Al-1Zn alloy. Acta Materialia 50(12):3265–3281CrossRefGoogle Scholar

Copyright information

© Springer 2008

Authors and Affiliations

  • Frank Czerwinski
    • 1
  1. 1.Development EngineeringHusky Injection Molding Systems Ltd.Bolton, OntarioCanada

Personalised recommendations